Field
This disclosure is generally related to computer networks. More specifically, this disclosure is related to resolving a name for a piece of content to obtain network addresses to one or more servers that can provide the content.
Related Art
The Internet protocol suite includes a set of communication protocols designed to connect endpoints, such as the Transmission Control Protocol (TCP), and the Internet Protocol (IP). In this protocol suite, IP packets are switched and routed based on their source and destination addresses, which serves as the primary building-block for the entire suite of Internet protocols today. Building on IP, TCP provides reliable end-to-end transmission, and a domain name system (DNS) provides a directory that maps user-friendly hostnames to IP addresses. Also, the hypertext transfer protocol (HTTP) names individual directories and pieces of content within a host. When a client desires a particular piece of web content today, the client first uses DNS to map the hostname to an IP address, and then sends a HTTP request to this IP address to receive the content from the host.
However, using the Internet protocol suite and DNS servers to access web content creates a performance bottleneck at the HTTP servers, because these HTTP servers need to individually answer each HTTP request for the same piece of content. To make matters worse, Internet users are primarily concerned with having access to content, not necessarily to hosts. For example, a user that desires to stream a high-definition video feed would prefer to obtain the feed from a nearby server that can provide a faster bitrate than from the primary host for the media stream.
This disconnect has given rise to several peripheral technologies today, such as content delivery networks (CDNs) and HTTP proxies, which are designed to optimize or improve content distribution. CDNs have evolved as a service that a content publisher may employ to better and more efficiently distribute their content worldwide. CDNs employ DNS redirection, typically by appending a special set of characters (e.g., a388.g.akamaitech.net) to the original hostname in the URL. This process is constructed so that when a local DNS server attempts to resolve the hostname requested by the client, the local DNS server instead resolves the hostname of a relatively local server belonging to the CDN. This address is returned to the client, which then fetches the content from the local CDN server.
HTTP proxies approach the same problem from the client-side to traffic on the publisher's HTTP servers, which help reduce congestion throughout the Internet. An organization deploys an HTTP proxy at a network location that allows the proxy to see all outgoing HTTP requests, and their respective responses. The proxy caches the responses, and then directly answers subsequent requests for the same content without the request ever making its way to the publisher's HTTP servers.
However, HTTP proxies are oftentimes difficult to deploy, because they are not acknowledged by either DNS servers or CDNs. For a client to take advantage of a local proxy, the client browser needs to be configured to send HTTP requests directly to the HTTP proxy, or the HTTP proxy needs to be placed at a network location directly on the path between the client and the server.
Additionally, recent research efforts are producing information-centric networking (ICN) to re-architect the entire network stack around content. In ICN, packets typically do not contain network addresses for a source and a destination of the packet. Rather, clients issue requests for named data objects (NDOs), and routers across the network route these requests directly through the network to a closest network node that stores a copy of the content, which returns a packet that includes the requested NDO to respond to the request. However, ICNs represent a major departure from the current Internet architecture, and are fundamentally incompatible with today's TCP/IP stack. This incompatibility is a significant obstacle for any sort of deployment, and has hindered quick adoption of ICN proposals.